They are merely ornamental.
Near the top of the image you can see the base of Juche Tower (Google Maps), a monument in Pyongyang on the bank of the Taedong river.
(the two large fountains are curiously not visible in this picture, though)
A DPRK tourism website states the following (emphasis mine):
The Juche Tower was built on the occasion of the 70th birthday of Kim Il Sung, by the River Taedong in 1982 (Juche 71). The tower has a 20 metre long torch which can be seen glowing throughout the night. [...]
In front of it is a group of three people standing 30 metres high. Each person in the trio carry a symbol of the emblem of the Worker's Party of Korea; a hammer, sickle and brush. Two large fountains that rise up to 150 metres can be seen on the Taedong River.
Note the fountains are described in a way which can only be construed as ornamental.